Modified silane treated pigments or fillers and compositions containing the same

ABSTRACT

The present invention is directed to a composition comprising a white pigment or extended white pigment surface treated with a silane having at least one functional group capable of reacting with acids and anhydrides, at least one polymeric material and a compatibilizer. Once treated, the pigment has improved processability and dispersibility in polymeric materials. Silanizing the pigment also enhances the brightness (increase whiteness and reduce yellowness) of the pigment.

FIELD OF THE INVENTION

[0001] The present invention relates to the surface treatment ofpigments, particularly white pigments, to improve dispersibility inpolymeric materials, processability, and performance characteristics ofthe pigments. The pigments are treated with an organosilicon compoundhaving at least one functional group that is capable of reacting with anacid or an anhydride. More specifically, the present invention relatesto polymeric compositions comprising the surface treated pigments of thepresent invention.

BACKGROUND OF THE INVENTION

[0002] The treatment of titanium dioxide pigments with organosiliconcompounds to improve dispersibility in a polymer matrix is well known inthe art. For instance, U.S. Pat. No. 4,061,503 to Berger et al. and U.S.Pat. No. 4,151,154 to Berger describe the treatment of particulatetitanium dioxide to improve its dispersibility in a resin or plasticmedium. The titanium dioxide contains on its surface a silane possessingat least two to about three hydrolyzable groups bonded to the silicon,and an organic group which contains a polyalkylene oxide group.

[0003] Further, U.S. Pat. No. 4,810,305 to Braun et al. discloses amodified hydrophobic pigment or filler containing 0.05 to 10 wt. % of anorganopolysiloxane having improved dispersibility in synthetic resins.U.S. Pat. Nos. 5,607,994 and 5,631,310, both to Tooley et al., disclosewhite-pigmented polymers (particularly, polyolefins such aspolyethylene) containing white pigments treated with at least one silaneor a mixture of at least one silane and at least one polysiloxane toimprove processability in compounding and to improve performanceproperties such as lacing resistance in a polymeric matrix, as well asother physical characteristics.

SUMMARY OF THE INVENTION

[0004] The present invention relates to a pigment surface treated with asilane having at least one functional group capable of reacting withacids and anhydrides. The surface treated pigment or extended whitepigment can then be compounded with at least one polymeric material andat least one compatibilizer.

[0005] The silane of the present invention useful for surface treatingthe pigments or extended white pigments has the following generalstructure:

R_(x)Si(R′)_(4-x)

[0006] wherein

[0007] R is a nonhydrolyzable functional group directly or indirectlybonded to the silicon atom such as epoxy, isocyanato, mercapto, andmixtures thereof;

[0008] R′ is a hydrolyzable group such as alkoxy, halogen, acetoxy orhydroxy or mixtures thereof; and

[0009] x is 1 to 3.

[0010] Preferably, the pigment or extended white pigment is titaniumdioxide.

[0011] The compatibilizer has at least one group which is acidic, or isan anhydride thereof.

[0012] The resultant polymer composition may further compriselubricants, as well as a variety of other conventional additives.

[0013] The silanized pigments of the present invention exhibit improvedprocessability, lower viscosity, increased lacing resistance, improveddispersion in polymeric materials and excellent optical propertiesincluding improved whiteness and yellowness index over the untreatedpigments. The polymeric compositions of the present invention may beused in an endless variety of articles and applications.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0014] In general, the present invention encompasses the whiteningtreatment of potentially any inorganic oxide particulate material, days,pigments, extended white pigments, and so forth. These materials aretypically from classes of materials referred to as fillers, pigments,and reinforcing materials such as inorganic particulate materials andfibers (such as glass fibers, aluminum fibers and steel fibers), and soforth. Such materials include aluminum trihydroxide, magnesiumhydroxide, calcined clays, kaolin clays, nanoclays, brass (with anoxidized surface), copper metal (oxidized at its surface), aluminummetal (oxidized at its surface), iron or steel (oxidized at itssurface), alumina, aluminum trihydrate, siliceous materials such asfumed silica, hydrated silica (precipitated silica), silica aerogels,silica xerogels, aluminum silicates, calcium magnesium silicate,asbestos, glass fibers, molecular sieves, Wallostonite, calciumcarbonate, carbon black (including lamp black), titanium dioxide(including titanium dioxide which contains HCl soluble alumina and/orsilica), calcium sulphate, magnesium sulfate, calcium carbonatecontaining a silica coating or agglomerated to silica, and the like. Inparticular, the present invention is especially useful for the surfacetreatment of white pigments or extended white pigments, and even moreparticularly for the surface treatment of titanium dioxide pigments.

[0015] The titanium dioxide, TiO₂, pigments useful in the presentinvention generally are in the rutile or anatase crystalline form andare commonly made by either a chloride process or a sulfate process. Theoptimum average particle size can range from about 0.005 to about 1micron. The TiO₂ pigments may also contain ingredients added thereto tofurther improve dispersibility characteristics or other properties suchas durability.

[0016] It has been found that the silane treatment of this invention canbe used not only for TiO₂ but also for so-called extended white pigmentssuch as calcium carbonate.

[0017] Additives and/or inorganic oxides are commonly added to thepigments and include but are not limited to aluminum, silicon, tin,triethanolamine, trimethylolpropane, phosphates, and so forth. Suchadditives are known to one of skill in the art.

[0018] “Silanized TiO₂” is defined herein as TiO₂ treated with either atleast one silane, or a mixture of at least one silane and at least onepolysiloxane (collectively referred to herein as organosiliconcompounds).

[0019] The silanes useful herein are those that have a functional groupcapable of reacting with anhydrides or acids, their hydrolyzates orcondensates thereof. Examples of such silanes include those havingepoxy, isocyanato, and mercapto groups. In preferred embodiments, thesilanes have epoxy groups.

[0020] Suitable silanes have the following general formula:

R_(x)Si(R′)_(4-x)

[0021] wherein

[0022] R is a nonhydrolyzable functional group directly or indirectlybonded to the silicon atom;

[0023] R′ is a hydrolyzable group such as alkoxy, halogen, acetoxy,hydroxy or mixtures thereof; and

[0024] x=1 to 3.

[0025] Examples of suitable silanes useful in carrying out the inventioninclude but are not limited toγ-(3,4-epoxycyclohexyl)ethyltrimethoxysilane such as Silquest® A-186,γ-glycidoxypropyltrimethoxysilane such as Silquest® A-187,γ-Glycidoxypropylmethyldiethoxysilane such as Silquest® Y-15078,2-(3,4-epoxycyclohexalethyltriethoxysilane such as Silquest® Y-11870),γ-isocyanatopropyltrimethoxysilane such as Silquest® A-1310,γ-mercaptopropyltrimethoxysilane such as Silquest® A-189, and so forth.All of the above mentioned Silquest® materials are available fromCrompton Corporation of Greenwich, Conn. Preferably, the silanesutilized include Silquest® A-187, Silquest® Y-11870and Silquest®Y-15078.

[0026] The silanes of the present invention may be used in combinationwith a lubricant including, but not limited to, polysiloxanes, siliconefluids, stearates, paraffin oils, fluorocarbon lubricants, and so forth.The polysiloxanes useful herein include polydimethylsiloxane andorganomodified polydimethylsiloxane. “Organomodified” refers to organicpendant groups on the molecules that may include polyalkylene oxidessuch as polyethylene oxide, polyether groups, vinylic groups, and soforth.

[0027] In one embodiment, a mixture of at least one silane with at leastone polysiloxane is advantageous in carrying out the invention. Suitablepolysiloxanes for use in combination with at least one silane have thefollowing general formula:

(R″_(n)SiO_((4-n)/2))_(m)

[0028] wherein

[0029] R″ is an organic or an inorganic group;

[0030] n is 0to 3; and

[0031] m is equal to or greater than 2.

[0032] Examples of useful polysiloxanes in carrying out the presentinvention include, but are not limited to, polydimethylsiloxane (PDMS),vinyl phenylmethyl terminated dimethyl siloxanes, divinylmethylterminated PDMS and the like, PDMS with polyether pendant groupsincluding Silwet® PA-1 available from Crompton Corporation. PDMS such asSilwet® L45, available from Crompton Corporation, is an example of aparticularly useful polysiloxane.

[0033] The silanes preferable for use in combination with thepolysiloxanes include those silanes described above such as2-(3,4-epoxycyclohexaethyl triethoxy silane such as Silquest® Y-11870,and γ-glycidoxypropyltrimethoxy silane such as Silquest® A-187. Thesilane/polysiloxane mixture is useful from about 0.1 wt. % to about 5.0wt. %, and preferably from about 1.0 wt. % to about 3.0 wt. %, based ona total weight of the silanized pigments. A preferred combination isabout 0.5 wt. % to about 1.5 wt. % of the silane(s), and about 0.5 wt. %to about 1.5 wt. % of the polydimethylsiloxane based on a total weightof the silanized pigments. The ratio of silane(s) to polysiloxane may befrom about 1:2 to about 2:1, with the preferred ratio being about 1:1.

[0034] In preparing the silanized pigment, the order of addition is notespecially critical and the pigment may be treated with the silane usinga number of different methods. For example, the silane can be eitheradded neat or in a pre-hydrolyzed form to a dry pigmentary base, or itcan be added into a slurry. The silane can be added during filtration,during drying, at a sizing operation such as a fluid energy mill, e.g.micronizer, or at a media mill. The silane may also be post blendedafter micronizing. One of skill in the art would be knowledgeable intreating the pigmentary base with the silane(s). For instance, mediamilling first involves reducing the viscosity of a high solids TiO₂pigment slurry by adjusting the pH in the range of about 7.5 to about 11with caustic or the like, or by contacting the slurry with a reducent,and then treating the slurry with an organosilicon reagent. The treatingstep is either preceded by and/or followed by media milling the highsolids slurry to reduce the TiO₂ particle size. The slurry is then driedas a product thereby eliminating the post drying manipulation to controlpigment properties such as particle size distribution.

[0035] The surface modification of pigments by may also be effectuatedby adding amino organosilane to a pigment dispersion directly in asuitable solids mixing apparatus. Postblending processes may also beemployed as well.

[0036] The description of the various preparation methods describedherein is intended for guidance purposes only, and is in no way intendedas a limitation on the scope of the present invention. One of skill inthe art would realize that there are various methods and modificationsof such methods which may be utilized to prepare the silanized pigmentsor fillers of the present invention. Such methods and modifications areseen to be within the scope of the present invention.

[0037] The polysiloxane addition may be made in conjunction with thesilane, or added to the already silanized pigment. The silane additionand polysiloxane addition is described in greater detail below.

[0038] If water, either liquid or vapor (steam), is present as acomponent of the process stream, hydrolysis of the hydrolyzable groupsof the silane will occur and the silane coating will bond to the TiO₂base. Pre-hydrolyzing the silane is a preferred step in treating theTiO₂ pigment with the silane. Hydrolysis of silanes is described ingreater detail in “Organofunctional Silanes” by Union Carbide (1991).

[0039] The treated pigment compositions of the present invention mayfurther comprise a compatibilizer. The compatibilizer comprises at leastone reactive group capable of reacting with the functional groups of theorganosilicone compound. If, however, the polymeric material itselfcomprises such a functional group, a compatibilizer may not be utilized.For instance, if a modified polyolefin polymer with such a functionalgroup is used, a compatibilizer may be superfluous. In the alternative,a compatibilizing compound may be added in addition to the polymericmaterial being utilized. In the case of a polymeric composition whereinthe polymeric material is an unmodified polyolefin without any reactivegroups, then a compatibilizer is additionally added to the composition.

[0040] Examples of useful compatibilizers include copolymers of ethyleneor propylene with anhydride or acid groups capable of reacting with thefunctional groups of the organosilicon compound such as an epoxy group.The copolymers useful herein include ethylene maleic anhydridecopolymers (EMAH), ethylene acrylic acid copolymers (EAA), ethylenemethacrylic acid copolymers (EMAA), propylene maleic anhydridecopolymers (PMAH), propylene acrylic acid copolymers (PAA), ethylenepropylene copolymers with maleic anhydride or acid functional groups(EPMAH or EPAA), olefinic ionomer resins such as ethylene ionomers, andso forth. Ethylene maleic anhydride copolymers (EMAH) andethylene-acrylic acid copolymers (EAA) are preferred.

[0041] Some specific examples of useful compatibilizers include ACX®ethylene-maleic anhydride copolymer resins from Allied SignalCorporation of Morristown, N.J., Primacor® ethylene-acrylic acidcopolymer resins from The Dow Chemical Company of Midland, Mich.,Surlyn® ionomer resins available from E.I. du Pont de Nemours andCompany of Wilmington, Del., and Nucrel® ethylene methacrylic acid(EMAA) copolymers also available from E.I. du Pont de Nemours andCompany. The compatibilizer is present in an amount from about 0.5 wt. %to about 20 wt. %, preferably from about 1.0 wt. % to about 10 wt. %,more preferably from about 1.0 wt. % to about 6.0 wt. %, and mostpreferably from about 3.0 wt. % to about 5.0 wt. % based on a totalweight of the mixture which include the treated TiO₂, polymer,compatibilizer, and any other components used in the mixture.

[0042] The silanized compounds of the present invention may be used incombination with any polymeric material with which such compounds aretypically used. The silane acts, in a sense, as a dispersion promoter,by increasing the compatibility or dispersibility of the inorganic oxideor other particulate material within the plastic or resin system inwhich it is supplied.

[0043] The polymers useful herein are known to those of skill in theart. The general classes of polymers suitable for use herein arethermoplastic or thermosetting polymeric resinous materials, and includebut are not limited to, the olefinic polymers including polyethylene andits copolymers and terpolymers, polybutylene and its copolymers andterpolymers, polypropylene and its copolymers and terpolymers;alphaolefins including linear or substantially linear interpolymers ofethylene and at least one α-olefin and atactic polyalphaolefins; rubberyblock copolymers; polyamides; polyesters such aspolyethyleneterephthalate and polybutyleneterephthalate; vinylicpolymers; acrylics; epoxies; polycarbonates; and so forth; and mixturesthereof. Preferably, the polymers are selected from the group consistingof polyethylene, ethylene copolymers, polypropylene, propylenecopolymers, and mixtures thereof.

[0044] Olefinic polymers, such as polyethylene, polypropylene andpolybutylene, are from a broad class of polymers typically referred toas polymers of ethylenically unsaturated monomers, and the copolymersand terpolymers of such polymers with higher olefins such as alphaolefins containing 4 to 10 carbon atoms, or vinyl acetate, and the like.

[0045] Olefins, i.e. ethylene, are often copolymerized with vinylmonomers such as acrylates or vinyl esters of carboxylic acid compounds.Specific acrylate monomers include acrylic acid, methacrylic acid,acrylamide, methacrylamide, methyl acrylate, methyl methacrylate,methoxyethyl methacrylate, methoxyethyl acrylate, and so forth. Vinylesters of carboxylic acids include vinyl acetate, vinyl butyrate and soforth. Commonly used polymers of this variety include, for instance,ethylene vinyl acetate, ethylene ethyl acrylate, ethylene n-butylacrylate, and ethylene methylacrylate.

[0046] Other useful polymeric resins include vinylic compounds such aspolyvinyl chloride; polyvinyl esters such as polyvinyl acetate;polystyrene, acrylic homopolymers, copolymers and terpolymers;phenolics; alkyds; amino resins; epoxy resins; polyamides;polyurethanes; phenoxy resins; polysulfones; polycarbonates; polyestersand chlorinated polyesters; polyethers; acetal resins; polyimides;polyoxyethylenes; and so forth.

[0047] Other useful polymers include various rubbers and/or elastomersincluding both natural and synthetic rubbers. Such polymers may becopolymerized, grafted, physically blending with various diene monomers,and so forth. Block copolymers are a commonly used elastomer and includepolymers formed of styrene, butadiene, isoprene and so forth. Morespecifically, styrene-butadiene-styrene, styrene-isoprene-styrene,styrene-ethylene/butylene-styrene, styrene-ethylene/propylene-styrene,and so forth. Other elastomers include natural rubber, i.e.polyisoprene; polyisobutylene; butyl rubbers; and so forth.

[0048] Some polymers preferable for use in combination with thesilanized compounds of the present invention include polyolefins such aspolyethylene, polypropylene, polyvinyl chloride, polyamides, polyestersand copolymers and terpolymers thereof.

[0049] “High loaded” TiO₂ may depend on the type of polymer used and maybe anywhere from about 40 wt. % TiO₂, up to about 90 wt. % TiO₂. Forinstance, in a polyolefin matrix, a high loaded TiO₂ would be about 50wt. % or more of the TiO₂ pigment, based on a total weight of polyolefinmatrix.

[0050] A wide variety of conventional additives may be optionally addedto the polymeric compositions of the present invention as is necessary,desirable or conventional for the intended end use. Such additivesinclude but are not limited to antioxidants, ultraviolet (UV)stabilizers, lubricants, thermal processing additives, and so forth.Such additives are known to those of skill in the art.

[0051] TiO₂ coated with organosilicon compounds can be incorporated witha polymer in a melted state to form the polymeric compositions of thepresent invention by any melt compounding technique known to those ofskill in the art. Generally, TiO₂ and polymeric resin are addedtogether, and are subsequently mixed in a blending apparatus thatapplies shear to the melted polymer. The polymeric resin is typicallycommercially available in a variety of forms including but not limitedto powder, granules, pellets, cubes, and so forth.

[0052] In a typical mixing operation, pigment and polymer are first dryblended while the polymer is still in a solid, pre-melted state. Thiscan be accomplished with simple processes such as by shaking in a bag orby tumbling in a closed container. More sophisticated methods includeblending apparatuses having agitators or paddles. The pigment and thepolymeric resin can be co-fed into mixers having an internal screw, i.e.an extruder device, which mixes the pigment and polymer prior to thepolymer achieving a molten state.

[0053] Melt blending the components may be accomplished using anyconventional equipment known to those of skill in the art includingsingle-screw extruders, twin-screw extruders including the broad rangetwin screw extruders and corotating twin screw extruders, high shearmixers, blender type mixers, and so forth. Twin-screw extruders arecommonly used. The melt blending can be accomplished during formation ofan article such as during a melt extrusion process. Melt extrusion canalso be combined with blow molding, for instance.

[0054] Exemplary mixers include co-rotating twin screw extrudersmanufactured by Werner & Pfleiderer in Ramsey, N.J., and by LeistritzExtruder Corporation in Somerville, N.J. Farrel Corporation in Ansonia,Conn. manufacturers the Farrel Continuous Mixers (FCM).

[0055] There are numerous ways of preparing the polymeric compositionsof the present invention. A concentrate may first be prepared having ahigh concentration of TiO₂, commonly referred to as a masterbatch, andthen subsequently combining the concentrate with polymeric resin.

[0056] The highly loaded polymer concentrates are made as describedabove with the desirable weight % of pigment for the intended end use.For example, in polyolefin concentrates, about 50 wt. % to 85 wt. %concentrate may be used to opacify the composition. The TiO₂ concentrateis “let down” into the polymer. As used herein, “let down” refers toprocess of lowering the TiO₂ concentration in a resultant polymer. Forexample, in optical property evaluation, a concentrate having about 50wt. % to about 87 wt. % TiO₂ may be let down to about 0.2 wt. % to about30 wt. % by dry mixing polyolefin, extruding at a specific temperature,and casting it into a film. The pigment performance is then evaluated inan end use application.

[0057] The highly loaded silanized pigmentary TiO₂ exhibits outstandingprocessibility in polyolefinic matrices, and excellent lacingresistance. The torque and pressure can be utilized to determine therelative ease with which the compositions are processed through a mixer,e.g. an extruder, for instance. The lower the torque and pressurerequired to mix and move the composition through the equipment, theeasier the processing. Furthermore, typically, the higher the loading ofpigment or filler, i.e. TiO₂, in a polymer concentrate, the slower theprocessing rates.

[0058] The compositions of the present invention require lower torqueand pressure for processing, particularly through an extruder, than dothose polymeric compositions compounded with untreated titanium dioxide,and faster processing rates can also be obtained. Another advantage ofthe polymeric films made using the pigmented compositions of the presentinvention, particularly those made with the silanized TiO₂ of thepresent invention, is increased lacing resistance. Other advantagesinclude increased bulk density, lower viscosity, excellent dispersion,excellent moisture resistance, and excellent optical properties such ashigh whiteness and gloss.

[0059] The polymeric materials containing the treated pigments of thepresent invention are useful in a variety of applications. The polymericcompositions of the present invention may be employed, for example, formolding (including extrusion, injection, calendering, casting,compression, lamination, and/or transfer molding), coating (includinglacquers, film bonding coatings and painting), inks, dyes, tints,impregnations, adhesives, caulks, sealants, rubber goods, and cellularproducts. Thus, the choice and use of the polymeric compositions withthe treated particles of this invention is essentially limitless.

[0060] One of ordinary skill in the art would understand that there area vast number of modifications which could be made without changing thescope of the invention, those modifications and embodiments thereof arecontemplated to be within the scope of the present invention.

[0061] The following non-limiting examples are further illustrative ofthe present invention, and are in no way intended to limit the scope ofthe present invention.

EXAMPLES

[0062] Test Methods

[0063] 1. Viscosity (Pascal/Second) and Melt Flow Index (g/10 Minutes)

[0064] The viscosity and melt flow index were measured at 190° C. usinga Tinius Olsen Extrusion Plastometer available from Tinius OlsenCorporation in Willow Grove, Pa.

[0065] 2. Yellow Index and Whiteness

[0066] The yellowness index and whiteness were measured using the filmsand plaques as prepared above using a Colorgard System™ 1000 calorimetermanufactured by Pacific Scientific Corporation in Silver Spring, Md.Film thickness was about 4 mils.

[0067] 3. Gloss

[0068] The gloss of the film and plaque samples was measured with aGL-4525 glossmeter manufactured by Paul N. Guard Co. in Pompano Beach,Fla. Film thickness was about 4 mils.

[0069] 4. Hue and Chroma

[0070] The hue and chroma of the film and plaque samples were measuredusing a Minolta® CR 231 chromameter available from Minolta Corporationin Osaka, Japan. The films tested had a thickness of about 4 mils.

[0071] 5. Dispersion

[0072] The dispersion of the pigment was tested using a light box. Filmthickness was approximately 1 mil. The dispersion is rated according tothe distribution and uniformity using a rating of excellent, good, fairand poor.

[0073] The following examples were prepared using a masterbatchconcentrate prepared in the following manner. The masterbatchconcentrate contained 80 wt. % TiO₂ in low density polyethylene (LDPE).The TiO₂ powder was treated with silane or a silane/siloxanecombination, and mixed with low density Microthene® GMN 711-20 LDPEavailable from Equistar Corporation in Houston, Tex., having a melt flowindex (MFI) of 22, and a compatibilizer which was an ethylene-maleicanhydride copolymer, ACX® 575 available from Allied Signal Corporationin Morristown, N.J., or Primacor® 2410, an ethylene-acrylic acidcopolymer available from The Dow Chemical Company, in Midland, Mich. Thecomposition was mixed in a Henschel dry mixer manufactured by ProdexCorporation in Fords, N.J. The dry mix was then fed into a twin screwextruder (ZSK 30 by Werner & Pfleiderer of Ramsey, N.J.) for a meltcompounding. The twin screw extruder was equipped with recordingequipment for recording temperature, pressure, rotating speed, torqueand power consumption. The extruded rods were fed into a water bath, airknife and pelletizer. The 80 wt. % high loaded TiO₂/LDPE pellets weredried at 140° F. (60° C.) for about 8 hours and then made into filmsusing a Brabender PL-V302 single extruder with a 6″ wide slot die. Thefilms were tested for dispersion of TiO₂ in LDPE using a light box.

[0074] The masterbatch was then let down to 8%. The balance of LDPE(Petrotheneg NA206, MFI™ 13 available from Equistar Corporation),antioxidant (1rganox® B-215 and 1010, from Ciba Specialty Chemicals inTarrytown, N.Y.) and ultraviolet stabilizer (Tinuvin® 783FP, also fromCiba Specialty Chemicals) were added into the Masterbatch pellets with abag dry mixing. The dry mix was fed into a 2″ single screw extruder(Midland Ross Hartic) for a melt compounding. The extruded strands wentthrough a water bath and pelletizer.

[0075] The let down pellets were made into film samples using aBrabender model PL-V302 single extruder with a 6″ wide slot die. Thedispersion of TiO₂ in LDPE was checked for these film samples with alight box. The film samples were also used for the measurement ofoptical performance (whiteness, yellow index, gloss, hue and chroma).

[0076] The let down pellets were also made into plaques by compressionmolding. Film thicknesses were approximately 4 mils.

Example 1

[0077] RCL-9™ pigmentary rutile TiO₂ supplied by Millenium InorganicChemicals in Baltimore, Md. (2500 g) was added to a Patterson-Kelly Twinshell V-Blender and sprayed with a solution of 25 g of A-187 γ-glycidoxypropyltrimethoxysilane available from Crompton Corporation. The solutionwas about 20 wt. % silane in 90/10 methanol/water. The silanized TiO₂(2400 g) was then dried in an oven at 140° F. (60° C.) for 8 hours.

[0078] The silanized TiO₂ was then compounded with 450 g of Microthene®GMN 711-20 LDPE having a MFI of 22 available from Equistar, and 150 g ofACX® 575 ethylene-maleic anhydride copolymer compatibilizer availablefrom Allied Signal. The compounding was accomplished using a twin screwextruder model ZSK 30 by Werner & Pfleiderer. The weight ratio oftreated TiO₂ to LDPE to compatibilizer was 80:15:5. The composition wasformed into pellets and film samples were prepared using a Brabendermodel PL V302 single screw extruder with a 6″ wide slot die.

Example 2

[0079] RCL-9 pigmentary rutile TiO₂ was treated with 1% γ-glycidoxypropyltrimethoxysilane and 1% L-45 polydimethylsiloxane (PDMS) availablefrom Crompton Corporation. The TiO₂ was first treated with theγ-glycidoxy propyltrimethoxysilane. The PDMS (24 g) was then mixed withthe silanized TiO₂ (2400 g), LDPE (450 g) and compatibilizer (150 g) ina Henschel mixer for about one minute at 2200 RPM as in Example 1. Thedry mix was then compounded through a twin screw extruder as in Example1.

Example 3

[0080] Example 1 was repeated using2-(3,4-epoxycyclohexal)ethyltriethoxysilane, Y-11870, available fromCrompton Corporation, instead of the γ-glycidoxypropyltrimethoxysilane.

Example 4

[0081] Example 2 was repeated using Silquest® Y-118702-(3,4-epoxycyclohexal)ethyltriethoxysilane, available from CromptonCorporation, instead of the γ-glycidoxypropyltrimethoxysilane.

Comparative Example A

[0082] Untreated RCL-9 TiO₂ was dry mixed with Microthene® GMN-711-20LDPE (MFI 22) using a plastic bag. The mix was then fed into a twinscrew extruder for compounding.

[0083] The results of the tests using Examples 1-4 and Comparative A aresummarized in Table I below. TABLE I Observations Torque during Example(ft-lb) Pressure (psi) Dispersion extrusion 1 1640 <25 good low feedrate but acceptable 2 1650 <25 good runs well, smooth surface 3 1780 <25good low feed rate but acceptable 4 1750  20 excellent runs well, smoothsurface Comparative 2600 400 a film could Brittle, rough A not be madeSurface, very difficult to process

[0084] The data found in Table I demonstrates the processing advantagesof using TiO₂ that has been treated with an organosilicone compound(Examples 14) as compared to an untreated TiO₂ (Comparative A) asopposed to using an untreated TiO₂ pigment (Comparative A) in a highloaded 80 wt. % TiO₂/polyethylene masterbatch. The torque and pressurecan be used as a means of determining the relative ease with which eachcomposition is processed through the extruder. As can be seen from thedata, the comparative example with the untreated titanium dioxiderequires both higher torque and higher pressure for processing thecomposition through the extruder.

[0085] Using the untreated TiO₂ lead to compounding difficulty in makinga high loaded 80 wt. % TiO₂ masterbatch with LDPE. Films could not bemade using the composition with the untreated TiO₂ Compounding wasaccomplished at a 30 wt. % level of TiO2.

[0086] The 30 wt. % loaded compositions were selected due to theincompatibility between untreated TiO₂ and LDPE. This incompatabilityresulted in difficulty in producing a masterbatch of LDPE filled withuntreated TiO₂. Furthermore, films of LDPE highly loaded with untreatedTiO₂ could not be successfully made. The untreated TiO₂could be used tosuccessfully produce a 30 wt. % loaded LDPE masterbatch, and films couldbe made thereof. Consequently, compounding experiments were conducted ata 30 wt. % loading of both treated and untreated TiO₂to ensure accuratecomparative results.

Comparative Example B

[0087] Untreated RCL-9 TiO₂ was dry mixed with Microthene® GMN 711-20LDPE (MFI 22) at a weight ratio of 30:70 using a plastic bag. Themixture was then fed into a twin screw extruder and compounded as inComparative Example A. The composition was formed into pellets dried.Film samples were prepared using a Brabender PL-V302 single extruderwith a 6″ wide slot die.

Example 5

[0088] Comparative example B was repeated except that the TiO₂ wastreated with 1% γ-glycidoxy propyltrimethoxysilane (A-187) availablefrom Crompton Corporation, and a compatibilizer (ACX® 575ethylene-maleic anhydride copolymer available from Allied Signal) wasadded. The weight ratio of treated TiO₂ to LDPE to compatibilizer was30:67:3.

Example 6

[0089] Example 5 was repeated using TiO₂ treated with 1% γ-glycidoxypropyltrimethoxysilane (A-187) and 1% PA-1 organomodifiedpolydimethylsiloxane available from Crompton Corporation The weightratio of treated TiO₂ to LDPE to compatibilizer was 30:67:3.

Example 7

[0090] Comparative example B was repeated using TiO₂ treated with 1%2-(3,4-epoxycyclohexyl)ethyltriethoxysilane (Y-11870), and acompatibilizer (ACX 575, ethylene-maleic anhydride copolymer) was added.The weight ratio of treated TiO₂ to LDPE to compatibilizer was 30:67:3.

Example 8

[0091] Example 7 was repeated using TiO₂ treated with 1%2-(3,4-epoxycyclohexal)ethyltriethoxysilane (Y-11870) and 1% PA-1organomodified polydimethylsiloxane. The weight ratio of treated TiO₂ toLDPE to compatibilizer was 30:67:3.

[0092] The viscosity and melt flow rate of the pellets were measuredusing an extrusion plastometer manufactured by Tinius Olsen. Thewhiteness and yellowness index of the film samples were measured using aColorgard® System 05 colormeter manufactured by Pacific Scientific. Theresults are summarized in Table 2 below. TABLE II Viscosity Flow RateWhiteness Yellowness Example (Pa/sec) g/10 minutes ASTM D 1925 ASTM D1925 Comparative 841.5 12.6 71 7.32 B 5 869.1 12.3 90 2.56 6 746.2 13.189 2.52 7 776.6 13.0 86 3.36 8 696.3 14.8 86 3.0

[0093] The data found in Table II demonstrates the improved processingparameters, lower viscosity, higher whiteness and lower yellownessachieved using the organosilicone treated TiO₂ pigments (Examples 5-8)versus using an untreated TiO₂ pigment (Comparative B) in a 30 wt. %TiO₂/polyethylene masterbatch. The viscosity and melt flow rate weremeasured using the pellets, and the whiteness and yellowness index weremeasured using films having a thickness of approximately 4 μm.

Comparative Example C

[0094] Comparative Example B was repeated using untreated ground CaCO₃.The weight ratio of untreated CaCO₃ and Microthene® GMN 711-20 LDPE (MFI22) was 30:70.

Example 9

[0095] Example 6 was repeated using ground CaCO₃ treated with 1%γ-glycidoxy propyltrimethoxysilane (A-187) and 1% L-45polydimethylsiloxane available from Crompton Corporation at Greenwich,Conn. The weight ratio of treated CaCO₃ to LDPE to compatibilizer (ACX575) was 30:67:3. TABLE III Whiteness Yellowness Example ASTM D 1925ASTM D 1925 Comparative C 22 20.89 Example 9 40 14.52

[0096] The data found in Table III demonstrates the higher whiteness andlower yellowness achieved using the organosilicone treated CaCO₃(extended white pigment, Example 9) versus using an untreated CaCO₃(Comparative Example C) in a 30 wt. % CaCO₃/polyethylene masterbatch.

Example 10

[0097] By weight, 20% of an epoxysilane (Silquest® A-187) treated TiO₂was compounded with 2% EMAH and balance polyethylene. Material wasextruded on a Brabender PL-V302 single screw extruder through a slitfilm die at 620° F. Evaluation of the film on a light box revealedsuperior integrity with no thin spots or pin-holes. Rating of materialequaled 10. Lacing resistance was comparable to the industry standardTi-Pure® R-104, available from E.I. du Pont de Nemours and Company.

Comparative Example D

[0098] By weight, 20% of an untreated TiO₂ pigment RCL-9 available fromMillenium Chemicals, Inc. in Baltimore, Md., was compounded into balancepolyethylene. Material was extruded on a Brabender PL-V302 single screwextruder through a slit film die at 620° F. The film exhibited thinspots and pin-holes under a light box. The material was rated as a 6.

[0099] Lacing occurs as a function of pigment volatility at specificwt-% pigment loadings and processing temperature. For polyethylene filmspigmented with titanium dioxide, 20% wt. % TiO₂ in the film processed attemperature of 620° F. or greater will readily exhibit lacing of thefilm. Typically, materials are rated 10 if they do not lace, and below10 if they begin to lace. Example 10 and comparative example D werecompared above for lacing.

[0100] Having thus described and exemplified the invention with acertain degree of particularity, it should be appreciated that thefollowing claims are not to be so limited but are to be afforded a scopecommensurate with the wording of each element of the claim andequivalents thereof.

1. A composition comprising: a) a white pigment or extended whitepigment surface treated with a silane having at least one functionalgroup capable of reacting with acids and anhydrides; b) at least onepolymeric material; and c) a compatibilizer.
 2. The composition of claim1 wherein said silane has the following general formula:R_(x)Si(R′)_(4-x) wherein R is a nonhydrolyzable functional groupdirectly or indirectly bonded to the silicon atom selected from thegroup consisting of epoxy, isocyanato, mercapto, and mixtures thereof;R′ is a hydrolyzable group selected from the group consisting of alkoxy,halogen, acetoxy or hydroxy or mixtures thereof; and x=1 to
 3. 3. Thecomposition of claim 1 wherein said pigment is TiO₂.
 4. The compositionof claim 1 wherein said extended white pigment is selected from clays,inorganic metal compounds and siliceous materials.
 5. The composition ofclaim 1 wherein said compatibilizer comprises copolymers of ethylene orpropylene with anhydride or acid groups which are capable of reactingwith the functional groups of the at least one polymeric material. 6.The composition of claim 1 wherein said compatibilizer comprisescopolymers selected from the group consisting of ethylene maleicanhydride copolymers, ethylene (meth)acrylic acid copolymers, propylenemaleic anhydride copolymers, propylene acrylic acid copolymers, ethylenepropylene copolymers with maleic anhydride or acid functional groups,and olefinic ionomer resins.
 7. The composition of claim 1 wherein saidcompatibilizer is present at a concentration of about 0.5 wt. % to about20 wt. % based on a total weight of the composition.
 8. The compositionof claim 1 wherein said compatibilizer is present at a concentration ofabout 1% to about 10% by weight of the total composition.
 9. Thecomposition of claim 1 wherein said filler or pigment is present at aconcentration of about 40 wt. % to about 85 wt. % based on a totalweight of the Composition.
 10. The composition of claim 1 furthercomprising at least one lubricant selected from the group consisting ofpolysiloxanes, silicone fluids, stearates, paraffinic oils, fluorocarbonfluids, and mixtures thereof.
 11. The composition of claim 10 whereinsaid lubricant is a polysiloxane selected from the group consisting ofpolydimethylsiloxane and organomodified polydimethylsiloxane.
 12. Thecomposition of claim 13 wherein said lubricant is present from about0.05 wt. % to about 5 wt. % based on a total weight of the composition.13. The composition of claim 1 wherein said silane is present on thesurface of said pigment or extended white pigment in an amount of about0.1 wt. % to about 5 wt. % based on a weight of said pigment or extendedwhite pigment.
 14. The composition of claim 1 wherein said polymericmaterial is selected from the group consisting of olefins andalphaolefins and their copolymers and terpolymers, rubbery blockcopolymers, polyamides, polyesters, vinylic polymers, acrylics, epoxies,ionomeric resins, and mixtures thereof.
 15. The composition of claim 14wherein said polymeric material is selected from the group consisting ofpolyethylene, ethylene copolymers, polypropylene, propylene copolymers,and mixtures thereof.
 16. A white pigment surface treated with at leastone silane capable of reacting with acids and anhydrides and having thefollowing general structure: R_(x)Si(R′)_(4-x) wherein R is anonhydrolyzable functional group directly or indirectly bonded to thesilicon atom selected from the group consisting of epoxy, isocyanato,mercapto, and mixtures thereof; R′ is a hydrolyzable group selected fromthe group consisting of alkoxy, halogen, acetoxy or hydroxy or mixturesthereof; and x=1 to
 3. 17. The white pigment of claim 16 wherein saidwhite pigment is selected from the group consisting of clays, inorganicmetal compounds and siliceous materials.
 18. The white pigment of claim16 wherein said white pigment is selected from the group aluminumtrihydroxide, magnesium hydroxide, calcined clay, nanoclay, kaolin clay,oxidized brass, oxidized aluminum, oxidized steel, alumina, aluminumtrihydrate, fumed silica, precipitated silica, silica aerogels, silicaxerogels, aluminum silicates, calcium magnesium silicates, asbestos,molecular sieves, Wallostonite, calcium carbonate, titanium dioxide,calcium sulphate, magnesium sulfate, calcium carbonates having a silicacoating, calcium carbonates agglomerated to silica, and mixturesthereof.
 19. The white pigment of claim 16 wherein said white pigment isTiO₂.
 20. A white pigment or extended white pigment having enhancedprocessability and dispersion in polymeric material surface treated witha silane having a structure of: R_(x)Si(R′)_(4-x) wherein R is anonhydrolyzable functional group directly or indirectly bonded to thesilicon atom selected from the group consisting of epoxy, isocyanato,mercapto, and mixtures thereof; R′ is a hydrolyzable group selected fromthe group consisting of alkoxy, halogen, acetoxy or hydroxy or mixturesthereof; and x=1 to 3; and a polysiloxane having a structure of:(R″_(n)SiO_((4-n)/2))_(m) wherein R″ is an organic or an inorganicgroup; n is 0to 3;and m is equal t o or greater than 2.